1. Field of the Invention
This invention relates to an absorption cooling and heating system, and more particularly to an absorption cycle having a solution concentrator between the absorber and the generator of the cycle.
2. Description of the Prior Art
Absorption cooling systems are well established in the prior art. In such systems, refrigerant vapor is absorbed in an absorber. The resulting absorbent-refrigerant solution is circulated to a generator in which it is heated. The refrigerant is separated from the absorbent-refrigerant solution and condensed after which it is recycled to an evaporator in which it is vaporized to be reabsorbed in the absorber and begin the cycle again. Such systems are generally taught by U.S. Pat. 2,212,869 and U.S. Pat. No. 4,594,856. In such systems, the thermal energy required to heat the generator is greater than or equal to the cooling effect provided by the evaporator.
In U.S. Pat. No. 4,402,795, a two stage generator process in which the output of the first stage generator is a more concentrated absorbent-refrigerant solution being fed to the second stage is disclosed. The thermal energy provided to the second stage generator is recycled by integrating the condenser for the second stage generator with the first stage generator. In such systems, the thermal energy required to heat the generators is greater than or equal to half the cooling effect provided by the evaporator.
Also taught by the prior art are methods of controlling the reliable performance of an absorption cooling system, most notably, U.S. Pat. No. 3,517,522 and U.S. Pat. No. 4,328,679 which teach techniques for adjusting and controlling absorbent solution concentrations, and U.S. Pat. No. 4,315,411 which teaches the use of additives to improve the heat transfer characteristics in the absorber assembly.
Absorption cooling system improvements have generally focussed on the absorbent-refrigerant solution, changing its concentration or composition to provide greater operating efficiency. See U.S. Pat. No. 4,485,638, U.S. Pat. No. 4,534,180, U.S. Pat. No. 4,593,531, U.S. Pat. No. 4,594,857, and U.S. Pat. No. 4,596,122.
Another cooling system improvement is disclosed in U.S. Pat. No. 4,152,904 which teaches the use of a solution concentrator, a single stage separation process in which refrigerant-absorbent solution is pumped under pressure to a membrane separation unit where the refrigerant is selectively passed through a membrane separator producing pure refrigerant. The refrigerant is then circulated through a heat exchange system for heating and/or cooling of the desired areas after which it is evaporated and circulated directly to an absorber where it is absorbed into the absorbent solution, generating the refrigerant-absorbent solution. The energy required to separate the refrigerant from the absorbent refrigerant solution is totally supplied by the pump and is equal to the energy which holds the refrigerant in the solution.
In a conventional absorption cooling cycle, heat applied to the generator to effectuate separation of the refrigerant from the absorbent-refrigerant solution is lost in a cooling tower or similar cooling process when condensing the refrigerant. Consequently, at least a portion of the sensible heat of the refrigerant is no longer available for doing useful work.